Ski bottom finishing method

ABSTRACT

A method for making snow skis with a bottom surface that provides relatively low friction with snow. The method produces a multiplicity of small, elongated, irregular indentations or striations in the bottom ski surface without grinding or buffing the hard plastic material forming the surface. It can also be applied to produce grooves of a predetermined size. The method includes the steps of providing a sandwich of elements forming the ski structure including a bottom member of plastic material, providing a metal form or die having a multiplicity of elongated indentations or striations in an upper surface, placing the indented surface of the metal form against the surface of the bottom member, and applying heat and pressure of predetermined amounts for a period of time to press the form against the ski structure, and thereby imprint the surface pattern of the form on the surface of the bottom member.

ilnited States Patent Eaton 14 1 Mar. 28, W72

[54] SKI BOTTOM FINISHING METHOD 1,273,422 9/1961 France ..280/1 1.13 LM [72] Inventor: Earl V. Eaton Petaluma Calm 1,457,826 9/1966 France ..280/11.13 L [73] Assignee: George E. Garcia, Novato, Calif. Primary EXami'1er-Benj3min Hersh Assistant Examiner-Milton L. Smith [22] Filed 1 1970 Attorney-Owen, Wickersham & Erickson l l. N 1 94 [2 1 App 57 ABSTRACT A method for making snow skis with a bottom surface that "280/1143 i fggg provides relatively low friction with snow. The method produces a multiplicity of small, elongated, irregular indenta- [58] held of Search "288/1 156/219 583 tions or striations in the bottom ski surface without grinding or buffing the hard plastic material fon'ning the surface. It can [56] References Cited also be applied to produce grooves of a predetermined size. The method includes the steps of providing a sandwich of ele- UNITED STATES PATENTS ments forming the ski structure including a bottom member of 3,549,461 12/1970 Bennett ..280/1 1.13 L X pl material, p ng a me l form r ie having a mul- 2,851,277 9/l 958 Holmberg et a]. ....280/l 1.13 LM tiplicity of elongated indentations or striations in an upper sur- 0 1 3 8/1965 Brown, j 11 13 LM face, placing the indented surface of the metal form against 3,276,784 10/1966 Anderson, Jr. ....2s0/11.13 LM the Surface of the bottom member, and pp y heat and 2 142,459 H1939 Sahy 0 n 280/1 L13 CT pressure of predetermined amounts for a period of time to 8 1L] 3 C press the form against the ski structure, and thereby imprint 3'4O8086 10/1968 Bennett 2 0/ 1 T the surface pattern of the form on the surface of the bottom FOREIGN PATENTS OR APPLICATIONS membel" 331,559 9/1958 Switzerland ..280/] 1.13 L 2 Claims, 6 Drawing Figures SKI BOTTOM FINISHING METHOD This invention relates to snow skis and more particularly to a method for making snow skis with a bottom surface having an extremely low coefficient of friction on snow.

The speed and efficiency obtainable by snow skis is dependent almost entirely on the snow engaging surfaces of the skis. Skiers and ski-makers have long sought to provide surfaces on skis that would produce a minimum of friction with the various types of snow encountered under different weather conditions. For a long period the surface treatment of skis made of wood included the use of base coatings and sealants to which other top dressings of wax and other substances were often applied to suit certain existing snow conditions. While such materials were reasonably effective they had the obvious disadvantages of wearing off with use and additional applications were required. Because of the inherent limitations of wood, skis made from other materials cam into use and utilized a bottom surface made from a hard plastic material. Such plastic materials were normally smooth but it was found that a completely smooth surface created a suction which increased friction between the skis and the snow and thereby limited speed and co'ntrolability. Attempts to overcome this problem were made by grinding or sanding the bottom ski surfaces with belts, wheels or discs: of varying types using grit or grit-like material. While-this surface treatment produced some favorable results on decreasing friction, the process had several severe disadvantages. The abrasive treatment, usually done with grinding wheels or sanding machine, created an irregular surface roughness with indentations of varying depth, width, size or coarseness. Moreover, it produced feathered" or ragged edges and multitudinous hair-like fibers on the surface of the plastic material. vAdditional hand or machine buffing failed to eliminate these irregularities and the surface fibers in snow increased the frictional drag of the ski. In addition to the unfavorable performance results produced by the grinding or sanding procedure, it also created severe dust problems for workmen while also being time consuming and, therefore, costly.

A general object of the present invention is to provide a method for making' snow skisthat solves the aforesaid problems and more particularly a method that provides a bottom surface having a multiplicity of elongated indentations or striations for reducing friction of the skis on snow without grinding, abrading, or otherwise removing material from the bottom of the ski. Moreover, the method provides for producing the striations in ski bottom surfaces having a predetermined characteristics to suitdifferent conditions and thereby provide maximum running efficiency.

Another object of the present invention is to provide a method for producing a textured ski bottom surface having no fiber-like particles, fuzz or feather edges thereon, and one that produces a surface having uniform characteristics from ski to ski.-

Yet another object of the present invention is To provide a method that can be performed with considerably less labor without the need for special grinding tools and in less time than previous methods for treating the bottom surfaces of skis.

Another object of my invention is to provide an improved method for making skis of both the conventional type as well as ski runners adapted for use on ski-bobs and other snow vehicles.

Still another object of my invention is to provide an improved laminated ski formed from a unique combination of wood, metal and plastic elements bonded together in a unitary structure and wherein the bottom surface with the desired texture of indentations may be formed when all of the elements are bonded together.

The above and other objects are accomplished by a method wherein elements of the ski are first assembled to form the desired sandwich. The sandwich includes top and bottom members of hard plastic material and various filler elements there between which are shaped to provide the desired taper for the ski. An elongated metal form is provided which is placed adjacent to the bottom surface of the bottom sandwich member before the entire ski sandwich is placed in a press. The surface of the form which engages the bottom ski surface is previously provided with a multiplicity of indentations or striations which may have a predetermined depth and cross sectional shape. The assembled ski elements and the bottom surface for are placed in a press and are held together under a suitable temperature and pressure. This simultaneously bonds the ski elements together and also imprints the textured surface in the plastic bottom of the ski. The method is fast, economical and produces uniform and highly effective results.

- Other objects, advantages and features of the present invention will become apparent from the following detailed description presented with the accompanying drawing, in which:

FIG. 1 is an exploded view in side elevation showing elements of a ski about to be made in accordance with the principles of my invention;

FIG. 2 is a view similar to FIG. 1 showing the ski elements sandwiched together before being placed in a press;

FIG. 3 is a fragmentary view taken at line 33 of FIG. 2 showing a section of the bottom surface form;

FIG. 4 is a view similar to FIG. 2 showing the ski sandwich within the press;

FIG. 5 is a fragmentary view taken at line 5-5 of FIG. 4 showing the surface of the ski; and

FIG; 6 is a view in a cross section of the ski taken at line 6- 60f FIG. '5.

With reference to the drawing, FIGfl shows the structure elements of a ski 10 embodying the principles-of the present invention. In the embodiment shown, these elements are comprised ofa core means 12 which, as seen in FIG. 6, may be a pair of spaced apart members. These core members are preferably made from a suitable wood material and are tapered from a maximum thickness near their mid-point toward each end. Above and below the core members are a pair of elongated sheet metal members 14 and 16. These latter members provide a large amount of the bending strength for the ski and are preferably made from a light but strong metal such as a suitable aluminum alloy. For example, I have found that a sheet of aluminum alloy having a thickness of around 0.010 to 0.060 inch is highly satisfactory as long as sufficient flexibility is maintained. Both of these metal members have a similar elongated shape with a tapered front end, which can vary depending on the size and type of ski.

Along the sides of the ski, the metal members 14 and 16 extend outwardly beyond the outside edges of the core members 12 and also slightly beyond an outer side strip member 18 on each core member (See FIG. 6). These strip members are preferably made of a hard plastic material having a smooth surface and each is bonded by a suitable adhesive to the outer side of one core member.

On top of the upper metal member 14 is a top member 20 having the same shape but being formed from a sheet of hard plastic material such as a polyolefin plastic. This top member is preferably provided with a smooth upper surface having an attractive color finish.

Below the lower metal member 16 is a bottom member 22 of the ski which is also formed from a hard plastic material such as a polyolefin plastic. For example, I. may use a sheet plastic material designated as polyolefin 990" which is available commercially under the trademark FORMICA. This bottom member is formed to substantially the same shape as the bottom metal member 16. However, along both sides of the upper surface of the bottom member are recesses 24 of uniform width. Bonded within these latter recesses are a pair of metal edge members 26 which are wider than the recesses and therefore extend outwardly a small distance (e.g., 1/16 inch) beyond the edges of the plastic bottom member 22. These metal edges are made from a relatively hard, durable metal such as steel and provide the sharp cutting edges necessary to give turning control to the ski.

The method steps for assembling the aforesaid elements of my ski and of simultaneously providing a permanent textured surface in the bottom of the ski in accordance with my invention will now be described,

In the first step of my method, a metal form 30 is prepared for use in fonning the bottom surface texturing. This form may be of a sheet metal such as mild steel, but preferably a metal that is hard enough to have formed in its surface 32 well defined indentations. These indentations may be produced in the form surface by any suitable means such as an abrading tool using abrasives such as diamond or tungsten carbide fragments. Preparation of the form surface to provide the proper density, length, depth and arrangement of surface indentations is important so as to produce the desired results on the ski bottom, but once accomplished, the form can be used for long production runs with no appreciable wear. For most purposes, the indentations should run generally longitudinally and are close together and at a depth of around 0.002 to 0.005 inch so that they form a multiplicity of small irregular ridges and the appearance of the form is that of a roughly abraded surface. Attached to the form and extending along its center line is a narrow unabraded strip of metal 36 having a thickness less than that of the bottom plastic member 22.

After the form has been prepared, the structural elements of the ski such as described above, including the bottom member 22, are now arranged together in the described sandwich. These sandwiched elements are placed in a press with the form 30 under the bottom member supported on a lower block 34 of the press which is shaped to define the camber or desired curvature of the finished ski. (See FIG. 2.) Before the press is closed, suitable adhesives are applied to the various elements of the ski, but of course no adhesive is applied between the form and the bottom surface of the ski. Now, the press is actuated to compress the elements together using a pressure in the range of 60 -l p.s.i. Simultaneously heat is applied (at around 250 400 F.) to help cure the adhesives and also cause the plastic of the bottom member to soften and ultimately flow and form the necessary indentations. As the form is pressed against the surface of the plastic ski bottom member, for a predetermined period, it makes a permanent imprint therein of its indentation pattern, thereby producing a roughened irregular striated pattern on the ski bottom which has no feather edges of fuzzy ends. The narrow strip 36 also displaces the heated plastic to form a center groove 38 in the ski bottom 22.

When the ski is removed from the press, the side edges are trimmed or dressed to a uniform surface, as shown in FIG. 6 and paint or decals can be applied were necessary.

The skis produced the aforesaid method have proven to have superior running characteristics when compared with skis constructed by prior methods wherein the bottom surfaces are roughtened by some abrading process. Moreover, the savings in time and labor afforded by my method result in a significant cost saving.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

1. A laminated ski comprising:

a core member tapering from an intermediate point of maximum thickness towards its opposite ends;

an upper metal member bonded to the upper side of said core member and a similar lower metal member bonded to the lower side of said core member;

a top member of hard plastic material bonded to said upper metal member and having a smooth outer surface;

a bottom member of hard plastic material bonded to said lower metal member and having a predetermined texture pattern of elongated irregular indentations without feather edges or fuzzy ends impressed on its bottom surface, said indentations having a depth of about .002 to .005 inchesand extending enerally parallel to the longitudmal axis of the ski, the ottom surface also having a central longitudinally extending groove of less depth than the thickness of said bottom member impressed therein. 2. A method for manufacturing a ski having a textured pattern of a multiplicity of irregular indentations and a central longitudinally extending groove on its bottom surface, said indentations having a depth of about 0.002 to 0.005 inch, said indentations being free of feather edges and fuzzy ends, comprising the steps of:

providing elements for forming the ski including a bottom lamination of hard plastic material; providing a form having an area at least as large as the area of said bottom ski lamination; surface treating said form to provide a roughened surface having a multiplicity of irregular ridges having a height of about 0.002 to 0.005 inch and also providing a raised portion of uniform width and thickness extending longitudinally along the center of the surface of said form, the thickness of said raised portion being less than the thickness of said bottom lamination; placing said form against the bottom surface of said bottom lamination and applying heat in the range of about 250 to 400 F. and pressure in the range of about 60 to p.s.i. to the form to press against the heat the bottom lamination to cause the form to imprint its pattern of irregular ridges on the bottom surface of the bottom lamination in a precise manner, without feather edges or fuzzy ends and also to imprint a longitudinally extending centrally located groove of uniform width and of a thickness less than the thickness of the bottom lamination on the bottom surface of said bottom lamination. 

1. A laminated ski comprising: a core member tapering from an intermediate point of maximum thickness towards its opposite ends; an upper metal member bonded to the upper side of said core member and a similar lower metal member bonded to the lower side of said core member; a top member of hard plastic material bonded to said upper metal member and having a smooth outer surface; a bottom member of hard plastic material bonded to said lower metal member and having a predetermined texture pattern of elongated irregular indentations without feather edges or fuzzy ends impressed on its bottom surface, said indentations having a depth of about .002 to .005 inches and extending generally parallel to the longitudinal axis of the ski, the bottom surface also having a central longitudinally extending groove of less depth than the thickness of said bottom member impressed therein.
 2. A method for manufacturing a ski having a textured pattern of a multiplicity of irregular indentations and a central longitudinally extending groove on its bottom surface, said indentations having a depth of about 0.002 to 0.005 inch, said indentations being free of feather edges and fuzzy ends, comprising the steps of: providing elements for forming the ski including a bottom lamination of hard plastic material; providing a form having an area at least as large as the area of said bottom ski lamination; surface treating said form to provide a roughened surface having a multiplicity of irregular ridges having a height of about 0.002 to 0.005 inch and also providing a raised portion of uniform width and thickness extending longitudinally along the center of the surface of said form, the thickness of said raised portion being less than the thickness of said bottom lamination; placing said form against the bottom surface of said bottom lamination and applying heat in the range of about 250* to 400* F. and pressure in the range of about 60 to 100 p.s.i. to the form to press against the heat the bottom lamination to cause the form to imprint its pattern of irregular ridges on the bottom surface of the bottom lamination in a precise manner, without feather edges or fuzzy ends and also to imprint a longitudinally extending centrally located groove of uniform width and of a thickness less than the thickness of the bottom lamination on the bottom surface of said bottom lamination. 